Near the end of September 2013, the National Renewable Energy Lab published a Western Wind and Solar Integration Study which showed conclusively that wind and solar energy reduces net pollution emissions on a virtually 1 for 1 basis. Anti-clean energy forces have spread the lie for years that because wind and solar are intermittent sources, just as much fossil fuel energy is still needed, thus resulting in no lowering of harmful emissions. NREL's study uses real world data demonstrating, as honest observers have noted, that wind energy directly displaces the output of the most expensive power plants, which are almost always the least efficient fossil-fired power plants.
In addition, the report concludes that boosting renewable production in the West to 25% of energy would save consumers billions of dollars.
An excellent summary of the report's highlights by Michael Goggin is here, and the NREL link is here.